In general, servovalves convert relatively low power electrical control input signals into a relatively large mechanical power output. Typically, servovalves receive a pressurized fluid from a fluid source to control a corresponding fluid motor. For example, during operation, pressurized fluid enters the servovalve and, based upon the control input signals, drives the fluid motor to operate nozzles or other variable-geometry elements associated with the fluid motor. Conventional servovalves include jet deflector servovalves and jet pipe servovalves.
FIGS. 1 and 2 illustrate an example of a jet deflector servovalve 10. The jet deflector servovalve 10 includes a torque motor 12 having a flexure tube 14, an armature 16 coupled to the flexure tube 14, and coils 18 oriented in electrical communication with the armature 16. The flexure tube 14 includes a deflector 20 defining an aperture 22, the deflector 20 oriented between a nozzle 24 and a pair of receivers 26 (e.g., a first receiver 26-1 and a second receiver 26-2). The first receiver 26-1 orients in fluid communication with a first chamber 32 defined by a spool 34 of the servovalve 10, via a first fluid pathway 36. The second receiver 26-2 orients in fluid communication with a second chamber 38 defined by the spool 34, via a second fluid pathway 40. As shown in FIG. 2, the nozzle 24 orients substantially opposite to (e.g., opposing within the same plane) the first receiver 26-1 and the second receiver 26-2. The nozzle 24 and deflector 20 are configured to direct pressurized fluid 28 from a pressurized fluid source 30 toward the receivers 26-1, 26-2.
During operation, the motor 12 receives a control signal input and transmits the control signal to the coils 18. The coils 18, in turn, generate a torque on the armature 16 to rotate the flexure tube 14 and adjust a position of the deflector 20 relative to the first receiver 26-1 and the second receiver 26-2. For example, as indicated in FIG. 2, assume the deflector 20 positions along a −X direction 44. With such positioning, the aperture 22 defined by the deflector 20 directs the pressurized fluid 28 from the nozzle 24 toward the second receiver 26-2 and blocks the first receiver 26-1 from receiving the pressurized fluid 28. The second receiver 26-2, in turn, directs the pressurized fluid 28-2 toward the second chamber 38 via the second fluid pathway 40, thereby creating an increase in pressure within the second chamber 38. Returning to FIG. 1, the increased pressure within the second chamber 38 pushes the spool 34 along a +X direction 42, allowing the source pressurized fluid 28 to flow to a fluid motor via port 46 to operate the fluid motor.
FIG. 3 illustrates an example of a jet pipe servovalve 60. The typical jet pipe servovalve 60, for example, includes a torque motor 62 having a flexure tube 64, an armature 66 coupled to the flexure tube 64, and coils 68 oriented in electrical communication with the armature 66. The flexure tube 64 includes a fluid jet 70 that couples to a fluid source 72 via a fluid pathway 74. The fluid pathway 74 extends from a second stage portion 73 of the servovalve 60 to a torque motor portion 75 of the servovalve 60. The fluid pathway 74 extends though the second stage 73 of the servovalve and directs the pressurized fluid through a top portion 77 of the servovalve assembly 60 to the fluid jet 70. The torque motor portion 75 of the servovalve 60 includes an o-ring 90 and the second stage portion 73 of the servovalve 60 includes an o-ring 88 opposing the o-ring 90. The o-rings 88, 90 minimize leakage of the pressurized fluid between the second stage portion 73 and the torque motor portion 75 during operation.
The jet pipe servovalve 60 also includes a fluid receiver 76 (e.g., a first receiver 76-1 and a second receiver 76-2). The first receiver 76-1 orients in fluid communication with a first chamber 78 defined by a spool 80 of the servovalve 60, via a first fluid pathway 82. The second receiver 76-2 orients in fluid communication with a second chamber 84 defined by the spool 80, via a second fluid pathway 86. The fluid jet 70 is configured to receive pressurized fluid from the pressurized fluid source 72 and direct the fluid toward the receivers 76-1, 76-2. The pressurized fluid source 72 delivers the fluid to a jet pipe assembly is configured with the pipe receiving fluid from the pressurized fluid source via the top of the servovalve assembly requires multiple o-rings to minimize leakage of fluid.
During operation, the motor 62 receives a control signal input and transmits the control signal to the coils 68. The coils 88, in turn, generate a torque on the armature 66 to rotate the flexure tube 64 and adjust a position of the fluid jet 70 relative to the receivers 76-1, 76-2. Such positioning changes the pressure in the respective chambers 78, 80 to adjust a position of the spool 80 within the servovalve 60.